1. Field of the Invention
The present invention relates generally to wireless networks, and more specifically, to a low power radio-frequency identification tag and system for determining the physical location of tagged items.
2. Background of the Invention
Radio-frequency identification (RFID) tags are becoming widespread for locating items such as store inventory and corporate assets, as well as for employee locating via RFID badges. Locating stations are typically part of a dedicated wireless system for receiving tag signals from the RFID tags. Reception information is gathered from multiple location stations and the location of the RFID tags is determined at a central master station.
The above-incorporated parent application discloses an RFID tag system using a Wireless Local Area Network (WLAN) channel that takes advantage of existing WLAN infrastructure to locate RFID tags. The tags provide low-power operation by using a “sniffer” to determine whether a WLAN channel is busy, and transmit only if the channel is free. The operation thus avoids generating interference with WLAN operations and other tags, and also reduces power consumption, as the sniffer circuit does not require the power that a complete receiver circuit would.
However, it is not possible for a sniffer circuit to determine whether or not the tag is being addressed by the WLAN system, as the sniffer does not include circuitry decode messages in order to determine a recipient. The tag also cannot receive commands or data. Therefore, the above-mentioned system is limited in that tag configuration and operational characteristics are fixed and cannot be adjusted by the system.
Therefore, it would be desirable to provide an improved RFID tag and method of operation, so that tags may be addressed while maintaining low power consumption and so that commands and/or data can be sent to the tag.